Automated blood sampling device

ABSTRACT

Devices are provided to automatically access blood from beneath or within skin. These devices include an injector configured to drive a needle into the skin and subsequently to retract the needle from the skin. These devices additionally include a seal to which suction is applied. To drive the needle into the skin, the needle is first driven through the seal, creating at least one hole in the seal. The suction applied to the seal acts to draw blood from the puncture formed in the skin by the needle, through the at least one hole in the seal, and to a sensor, blood storage element, or other payload. These devices can be wearable and configured to automatically access blood from skin, for example, to access blood from the skin at one or more points in time while a wearer of a device is sleeping.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and incorporates by reference thecontent of U.S. Non-Provisional patent application Ser. No. 14/635,643,filed Mar. 2, 2015, in its entirety and the content of U.S.Non-Provisional patent application Ser. No. 15/660,725, filed Jul. 26,2017, in its entirety.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Certain medical states or conditions of a human body can be detected bydetecting one or more properties of blood in the body. In some examples,such medical states can be detected by extracting a sample of the bloodfrom the body and detecting the one or more properties of the extractedblood using a sensor or other system external to the body. For example,a lancet or other skin-penetrating device could be used to penetrate theskin such that blood is emitted from the skin and/or such that blood canbe caused to be emitted from the skin. In another example, a needle,tubing, and other equipment could be used to access blood in an arteryor vein of a body. Blood accessed from a body can be exposed to a sensor(e.g., a sensor placed in contact with blood at the surface of skin thathas been penetrated). Additionally or alternatively, accessed blood canbe stored for later analysis. In a particular example, a lancet can beused to penetrate skin, allowing blood to be emitted from the skin suchthat a blood glucose level of the blood can be measured using anelectrochemical sensor placed in contact with the emitted blood.

SUMMARY

Some embodiments of the present disclosure provide a system including:(i) a needle configured to penetrate skin; (ii) an injector configuredto drive the needle into the skin to form a puncture in the skin andsubsequently to retract the needle from the skin; (iii) a suction sourceconfigured to provide suction; and (iv) a seal configured to receivesuction provided by the suction source, wherein the injector isconfigured to drive the needle through the seal to form at least onehole in the seal, and wherein the suction provided by the suction sourceis configured to draw blood from the formed puncture in the skin throughthe formed at least one hole in the seal.

Some embodiments of the present disclosure provide a system including:(i) penetrating means configured to penetrate skin; (ii) injector meansconfigured to drive the penetrating means into the skin to form apuncture in the skin and subsequently to retract the penetrating meansfrom the skin; (iii) suction means configured to provide suction; and(iv) a seal configured to receive suction provided by the suction means,wherein the injector means are configured to drive the penetrating meansthrough the seal to form at least one hole in the seal, and wherein thesuction provided by the suction means is configured to draw blood fromthe formed puncture in the skin through the formed at least one hole inthe seal.

Some embodiments of the present disclosure provide a method including:(i) mounting a system to skin, wherein the system comprises: (a) aneedle configured to penetrate the skin, (b) an injector, (c) a suctionsource, and (d) a suction seal configured to receive suction provided bythe suction source; and (ii) operating the injector to drive the needleinto the skin to form a puncture in the skin and subsequently to retractthe needle from the skin, wherein operating the injector to drive theneedle into the skin further comprises driving the needle through theseal to form at least one hole in the seal, and wherein the suctionprovided by the suction source is configured to draw blood from theformed puncture in the skin through the formed at least one hole in theseal.

These as well as other aspects, advantages, and alternatives, willbecome apparent to those of ordinary skill in the art by reading thefollowing detailed description, with reference where appropriate to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an exploded view of an example device.

FIG. 1B is a cross-sectional view of the example device of FIG. 1A.

FIG. 2A is a cross-sectional view of an example device mounted to a skinsurface.

FIG. 2B is a cross-sectional view of the example device of FIG. 2A whena needle of the example device is piercing the skin.

FIG. 2C is a cross-sectional view of the example device of FIG. 2B whenthe needle of the example device has retracted from the skin.

FIG. 2D is a cross-sectional view of the example device of FIG. 2C whenblood from the skin has been suctioned to a sensor of the exampledevice.

FIG. 3 illustrates an example piston and needles of a device.

FIG. 4 is a cross-sectional view of an example device.

FIG. 5A is a perspective top view of an example body-mountable device.

FIG. 5B is a perspective bottom view of the example body-mountabledevice shown in FIG. 5A.

FIG. 6A is a perspective top view of an example body-mountable device.

FIG. 6B is a perspective bottom view of the example body-mountabledevice shown in FIG. 6A.

FIG. 7 is a block diagram of an example system that includes a pluralityof wearable devices in communication with a server.

FIG. 8 is a functional block diagram of an example device.

FIG. 9 is a flowchart of an example method.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying figures, which form a part hereof. In the figures, similarsymbols typically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, figures, and claims are not meant to be limiting. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the scope of the subject matter presented herein. It willbe readily understood that the aspects of the present disclosure, asgenerally described herein, and illustrated in the figures, can bearranged, substituted, combined, separated, and designed in a widevariety of different configurations, all of which are explicitlycontemplated herein.

Further, while embodiments disclosed herein make reference to use on orin conjunction with a living human body, it is contemplated that thedisclosed methods, systems and devices may be used in any environmentwhere the operation of a device to extract a fluid from an environmentof interest by piercing a barrier and/or penetrating an element withinthe environment of interest is desired. The environment may be orinclude any living or non-living body or a portion thereof, a gel, anemulsion, a fluid conduit, a fluid reservoir, etc.

I. OVERVIEW

A body-mountable, wearable, handheld, desktop, or otherwise-configureddevice may be configured to access blood within a living body (or toaccess some other fluid in some other environment of interest). Such ablood-accessing device could include means for penetrating or piercingthe skin to allow the blood to be emitted from the skin. Suchpenetrating or piercing means could include one or more needles driveninto the skin by an injector incorporating chemical propellants,mechanical or electromechanical elements, or some other elements orcomponents configured to drive the one or more needles into the skin andsubsequently to retract the one or more needles from the skin to allowblood to be emitted from the skin via one or more punctures or otherpenetrations in the skin formed by the one or more needles. Such ablood-accessing device could additionally include suction means forapplying suction, through one or more formed holes in a seal, to drawblood into the device to be measured, detected, collected, stored, orotherwise used for some application (e.g., to draw blood into acollection chamber of the device). For example, the blood-accessingdevice could include a sensor configured to detect glucose in bloodreceived by the device from the skin. Additionally or alternatively, theneedle driven into the skin could be a hollow needle, and suction couldbe applied through the hollow needle to draw blood into the device,through the hollow needle, when the needle is penetrating the skin. Abody-mountable blood-accessing device could include multiple needles,injectors, seals, suction sources, sensors, blood storage elements, orother components such that the body-mountable blood-accessing devicecould be operated to automatically access blood from a wearer at anumber of specified points in time, e.g., while the wearer sleeps.

Blood could be accessed by devices and systems described herein for avariety of applications. One or more properties of accessed blood couldbe measured or detected (e.g., by a sensor of a blood-accessing device,or by some other system that could be exposed to blood accessed and/orstored by such a blood-accessing device). For example, a viscosity ofthe blood, a concentration or state of one or more analytes in theblood, or some other property of the blood could be detected. Forexample, a concentration of glucose, of insulin, of one or morehormones, or of some other substance could be detected. Such analytes,and detected concentrations or other properties thereof, could berelated to a health state of a person and could be used to determinesuch a health state. Further, such determined health states could beused to determine and/or indicate some medical or other action to betaken, for example, to take a dose of medicine (e.g., insulin), toperform an exercise, to seek medical attention, or some other action.Additionally or alternatively, detected analyte concentrations or otherproperties of blood accessed at a plurality of points in time couldallow for the determination of one or more physiological baselines orother physiological properties of a person (e.g., a baseline bloodglucose concentration, a baseline daily blood glucose profile) and/orthe determination and/or modification of a medical treatment regimen(e.g., a timing, dosage, or other property of application of a drug to aperson).

An injector or other means configured to drive one or more needles orother means for penetrating skin could be configured in a variety ofways to provide a force to drive the one or more needles into the skinand subsequently retract the one or more needles. For example, theinjector could include a piston disposed in a chamber and to which theone or more needles are coupled; a propellant could be used to applypressure behind the piston to drive the piston, and attached one or moreneedles, forward such that the one or more needles are driven into theskin. A spring or other means could also be provided to apply a force toretract the one or more needles subsequent to being driven into theskin. In a particular example, the propellant could include a chemicalor other material (e.g., nitrocellulose) that could be ignited (e.g., bybeing heated to an ignition temperature by, e.g., a resistive heatingelement) to produce gases that could apply pressure on the piston todrive the needle into skin. In another example, the propellant couldinclude compressed gases introduced into the chamber (e.g., by opening avalve, by puncturing a seal, by electrochemically generating the gases,by chemically generating the gases) and the compressed gases could applypressure on the piston to drive the needle into skin. Additionally oralternatively, an injector could include preloaded springs, magneticelements coupled to cams, motors, solenoids, ultrasonic vibrators, orother elements configured to drive one or more needles into skin.

A suction source or other suction means configured to provide suction toa seal and to draw blood through one or more holes formed in such a seal(e.g., by one or more needles being driven through the seal) and/or todraw blood into a device by some other means (e.g., through a hollowneedle) could provide suction by a variety of mechanisms. In someexamples, the suction source could include a pump, an endobaric chemicalprocess, a spring-loaded volume, or some other actuated element(s)configured to be operated to reduce a pressure to which the seal isexposed or to otherwise provide suction to the seal. In some examples,the suction source could include an evacuated volume, i.e., an enclosedvolume having a lower pressure than the atmosphere surrounding thedevice such that, when the seal is breached, blood (or some other fluidor material) is drawn through/toward the one or more holes in the seal.

Such suction provided to a seal and/or through one or more holes formedin the seal could act to draw the skin toward the seal. In someexamples, the device could include a concave depression (e.g., aspherical dome depression) formed in the seal and/or in some otherelement(s) of the device such that the suction provided by the suctionsource could draw a portion of the skin into the concave depression.Such displacement of the skin could act to increase a rate and/orduration of the emission of blood from the skin. A blood-accessingdevice could additionally or alternatively be configured in other waysto increase the rate and/or duration of the emission of blood from theskin following penetration by one or more needles. In some examples,heparin or some other anti-clotting or anti-coagulating substance couldbe introduced on/in the skin (e.g., by being deposited and/or injectedby the one or more needles). In some examples, an amount of blood flowin the skin could be increased by, e.g., applying suction to the skin(e.g., using the same or a different suction source as is used to drawnblood through the seal), applying a frictive force to the skin (e.g., byrubbing the skin), and/or heating the skin before driving the one ormore needles into the skin.

Blood accessed by devices as described herein (e.g., by driving one ormore needles into skin and applying suction to the skin to draw bloodout of the skin and into the device) could be used for a variety ofapplications. In some examples, the device could contain a sensor thatcould be configured to detect one or more properties of the blood (e.g.,to detect the concentration of an analyte in the blood). Such sensorscould operate based on contact between the blood and one or moreelements of the sensors (e.g., an electrode of an electrochemicalsensor). Alternatively, such sensors could be non-contact sensors (e.g.,colorimetric or other optical sensors). Sensors could be configured todetect glucose, blood cell counts, electrolytes, hormones, cholesterol,or some other analytes in accessed blood.

Additionally or alternatively, devices as described herein could beconfigured to store accessed blood for later use, e.g., forinterrogation by sensors or other elements of some other devices orsystems. For example, devices could access blood from skin and store theaccessed blood; later, the stored blood could be presented to a desktopsensor device or to some other system configured to receive the storedblood and to detect one or more properties of the provided blood.Storing blood could include providing heparin or other stabilizingand/or anti-clotting agents such that the blood is stored as a fluid.Additionally or alternatively, accessed, stored blood could be allowedto dry, clot, coagulate, or engage in some other process, and the driedor otherwise altered stored blood could be presented to a sensor deviceconfigured to receive the stored blood. In some examples, one or moreblood-storing elements of a blood-accessing device could be removable,and could be removed from the device to be presented to another systemfor analysis (e.g., the removable blood-storing aspects of the devicecould be removed and sent to a centrally located laboratory).

In some examples, a blood-accessing device may include a user interfacethat is configured to provide user-discernible indications (e.g.,visual, audible, and/or tactile indications) of the operation of thedevice to access blood and/or information about accessed blood sensed bysensors of the device, progress or other information related to afunction of the device, or other information. In some examples, the userinterface could additionally provide a means for one or more settings ofthe device (e.g., timing of one or more future activations of the deviceto access blood from skin, a user information privacy setting, a user'scredentials to access a service) to be specified by a user according tothe user's preferences. In some examples, the device may include awireless communication interface that can transmit/receive data to/froman external device, for example, using Bluetooth, ZigBee, WiFi, and/orsome other wireless communication protocol. The data transmitted by thewireless communication interface may include data indicative of one ormore physiological parameters or health state measured and/or determinedbased on blood accessed by the device. The wireless communicationsinterface could additionally or alternatively be configured to receivedata from an external system.

It should be understood that the above embodiments, and otherembodiments described herein, are provided for explanatory purposes, andare not intended to be limiting. Further, the terms ‘access,’‘accessed,’ ‘accessing,’ and any related terms used in relation to theoperation of a device to induce emission of blood from skin are usedherein (unless otherwise specified) to describe any operation orconfiguration of a device or system to receive blood from skin or fromsome other tissue. This could include receiving blood that has beenemitted from skin in response to cutting, piercing, incising, cutting,or otherwise penetrating the skin. This could include actively pulling,wicking, suctioning, or otherwise drawing such emitted blood from theskin and/or form the surface of the skin into the device and/or towardsome sensor, storage element, or other element(s) of the device.Further, while examples and embodiments described herein refer toaccessing blood from skin, it should be understood that methods,devices, and other embodiments described herein could be employed toaccess other fluids from other environments of interest.

II. EXAMPLE OPERATION OF DEVICES TO ACCESS BLOOD

A device could be configured in a variety of ways to access blood fromskin or from some other tissue. Such a device could include a variety ofpenetrating means (e.g., one or more needles) configured to be driveninto the skin by injecting means (e.g., by a piston and a chemicalpropellant) and subsequently retracted from the skin (e.g., by a spring)such that blood can be emitted from the resultant wound (e.g., puncture)in the skin. Further, such devices could include a variety of means(e.g., suction sources, seals, channels, concave depressions) configuredto draw blood out of the skin, to draw blood emitted from the skin intothe device, and/or to direct such accessed blood toward one or moresensors, blood storage elements, or other elements of the device.Further such devices could include additional elements, sensors,controllers, user interfaces, power sources, communications interfacesor other elements according to an application.

Such blood-accessing devices could be configured to be used to access,detect, store, or otherwise interact with blood in a variety of ways. Insome examples, such devices could be configured to be mounted to skin orotherwise worn such that the device can access blood automatically,e.g., a controller or other element(s) of the device could operate aninjector of the device to pierce the skin and access blood while awearer of the device sleeps. Alternatively, the device could be ahandheld device configured to be manually mounted to a portion of skinand operated to access blood from the skin. In some examples, the devicecould be wall-mounted, situated on a desktop, or disposed or mounted insome other way, and mounting the device to skin could includepositioning an arm or other aspect of a body proximate to the device(e.g., positioning skin of the wrist of a person proximate to aspecified aspect of the device). In some examples, one or more elements(e.g., injectors, needles, seals, suction sources, sensors, bloodstorage elements) could be removable from the device, e.g., such thatother elements of the device (e.g., controllers, user interfaces,mounts) could be reusable by replacing used removable elements of thedevice.

Blood accessed using devices and methods disclosed herein could be usedfor a variety of applications. Such applications could include anyapplications where one or more properties of a person and/or of blood ofthe person can be detected or determined from a volume of blood accessedusing such devices. The volume of blood can be related to theconfiguration of the device, and could be between approximately one andapproximately 10 microliters. For example, the device could beconfigured to access (e.g., to penetrate the skin and to apply suctionto the skin to draw) more than approximately 3 microliters of blood andto detect the concentration of one or more analytes (e.g., glucose,hormones, blood cells) in the accessed blood. The device could beconfigured (e.g., a stroke length, diameter or shape of a needle, theshape of a concave depression into which skin could be drawn by suction,an amount of applied suction) to provide a specified minimum amount ofblood according to a property of the blood to be measured and/or asensor used to detect such a property. For example, the device could beconfigured to access sufficient blood to allow detection of a glucoselevel of the blood using a low-power electrochemical sensor disposed inthe device. In another example, the device could be configured to accessand store a sufficient amount of blood to allow detection of a propertyof the blood by some other device or system that is provided with thestored blood from the blood-accessing device.

An example of such a blood-accessing device is illustrated in FIGS. 1Aand 1B. The device 100 includes six sections, with each sectionincluding a respective skin-penetrating needle, injector configured todrive the needle into the skin, suction source and sensor, among othercomponents. FIG. 1A shows an expanded perspective view of components ofthe first section of the device (components of other section of thedevice 100 are omitted for illustrative clarity). FIG. 1B is across-sectional view of the device 100 illustrated in detail elements ofthe first section of the device 100. The device 100 includes a housing110 that is formed to include a number of chambers (e.g., 131) andevacuated volumes (e.g., 141) of the sections as well as other features.Blood-accessing device 100 could be used on its own (e.g., by placing abottom surface of the device 100 in contact with skin), could be part ofanother device (e.g., part of a wrist-mountable or otherwisebody-mountable device), could be a removable module of another device,or could be configured or operated in some other way.

The first section includes elements disposed within a first chamber 131formed in the housing 110. The chamber is shown as a cylindrical shapeformed in the housing, but could assume other shapes according to anapplication. The chamber contains a needle 120 configured to penetrateskin, a piston 130 coupled to the needle 120 and configured to slidablymove within the chamber 131 (e.g., along the long axis of the chamber131), and a propellant 135 configured to slidably move the piston 130within the chamber 131 to drive the needle 120 into skin and further todrive the needle 120 through a seal 143 disposed on a bottom surface ofthe housing. The chamber additionally contains a spring 137 configuredto retract the needle 120 from the skin, a sealant layer 139 that isconfigured to be pierced by the needle 120 and a resistive element 136configured to ignite the propellant 135 by providing sufficient heat tothe propellant 135 when current passes through the resistive element136.

The top of the chamber 131 is closed by a circuit board 115 or othermember bonded or otherwise adhered to the housing 110. Electronics 150(e.g., one or more controllers, logic gates, current sources, electronicswitches, radio transceivers, analog-to-digital converters) disposed onthe circuit board 115 could be configured to perform operations of thedevice 100, e.g., to apply current to the resistive element 136 (or toother resistive elements or to operate other components of otherinjectors of the device 100) to ignite the propellant 135 at a specifiedpoint in time, to operate a sensor to detect a property of bloodaccessed from skin by the device 100, or to perform some otheroperations according to an application.

A needle channel 121 is formed in the bottom of the chamber 131 throughthe housing 110 such that the needle 120 can be driven into skinproximate the bottom of the housing 110. A piston vent 133 is formedthrough the piston 130 and chamber vents 132 are formed in the housing110 to allow gases produced by the ignition of the propellant 135 to bevented out of the device such that the spring 137 can retract the needle120 subsequent to the ignited propellant 163 causing the piston 130 todrive the needle 120 through the seal 143 and into skin. The diameter,number, geometry, and other properties of the vents 133, 132 could bespecified to control a force with which the piston 130 drives the needle120, a duration of time during which the needle 120 penetrates skinbefore being retracted by the spring 137, or other properties ofoperation of the device 100.

The seal 143 includes a concave depression 123 through which the needle120 penetrates the seal 143 to form a hole in the seal 143 when drivendownward by the piston 130. A channel 145 is formed above the concavedepression 123 behind the seal 143 and connecting the region behind theseal 143 with an evacuated volume 141 formed in the housing 110. The topof the evacuated volume 141 is sealed by the circuit board 115.Atmospheric gases are prevented from entering the evacuated volume 143through the chamber 131 by the sealant layer 139 and prevented fromentering the evacuated volume 141 through the bottom of the housing 110(e.g., through the concave depression 123) by the seal 143. A sensor 140is contained within the evacuated volume 141. The pressure in theevacuated volume 141 is sufficiently lower than the pressure of theenvironment surrounding the device 100 that, when one or more holes areformed in the seal 143 by the needle 120, the evacuated volume 141 actsas a suction source to draw blood from skin, through the one or moreholes in the seal 143, through the channel 145, and into contact withthe sensor 140 such that the sensor 140 can detect one or moreproperties of the blood (e.g., a glucose concentration of the blood). Insuch an example, the evacuated volume 141 additionally acts as acollection chamber for blood. The evacuated volume 141 could have apressure less than approximately 50 kilopascals. Other elements of thedevice 100 (e.g., the channel 145, the concave depression 123, theneedle channel 121, a hollow channel formed in a hollow needle of thedevice (e.g., in examples where the needle 120 is hollow), or some otherelements of the device 100 could act as a collection chamber for blooddrawn from skin by a suction source.

The device 100 additionally includes a conformal layer 170 configured toconform to the skin such that suction applied by the evacuated volume141 (or by some other suction source of the device 100) through one ormore holes in the seal 143 is applied to skin proximate the one or moreholes in the seal 143. This could include the conformal layer 170including polyurethane, soft rubber, polymeric gel, or some othercompliant material. Additionally or alternatively, the conformal layer170 could include a glue (e.g., cyanoacrylate), a tape, a dry adhesive,or some other adhesive substance.

FIGS. 2A-D illustrate the operation of the device 100 to access bloodfrom skin 105. FIG. 2A shows the device 100 having been mounted to theskin 105; this could include the device 100 being adhered to the skin105 using an adhesive or mount (e.g., a mount configured to encircle awrist of a person such that the device 100 is maintained in contact withskin of the wrist). Alternatively, the device 100 could be a handhelddevice designed to be manually or otherwise maintained in contact withthe skin 105. In another example, the device 100 could be a desktop orother relatively immobile device and a body part comprising the skin 105could be positioned proximate the device 100 as illustrated.

FIG. 2B shows the propellant 135 expanding to slidably move the piston130 downward, compressing the spring 137 and driving the needle 120 topierce the seal 143 and further driving the needle 120 into the skin105. Properties of the spring 137 (e.g., a spring constant, a degree ofinitial loading), piston 130 (e.g., a mass, a coefficient of frictionwith the sides of the chamber 131, a diameter and number of piston vents133), needle 120 (e.g., a diameter, a tip geometry, the presence of afluoropolymer coating or other anti-friction coating), chamber 131(e.g., a geometry, a volume of the region above the piston), propellant135 (e.g., an amount of the propellant, a mix of chemicals comprisingthe propellant), or other elements of the device 100 could be specifiedto maximize the speed with which the needle 120 is driven into the skin105 to, e.g., reduce discomfort induced in a user by operation of thedevice to penetrate the skin 105.

FIG. 2C shows the piston 130 and needle 120 retracted from the skin 105partially due to venting of propellant gases through the piston vent 133and chamber vents 132 (indicated by the arrow) and the force generatedby the spring 137 due to compression of the spring 137 by the movementof the piston 130 downward when driving the needle 120 into the skin 105(shown in FIG. 2B). FIG. 2C additionally shows a hole 144 formed in theseal 143 and a puncture 107 formed in the skin 105 by the piston 130driving the needle 120 through the seal 143 and into the skin 105. Thehole 144 in the seal 143 allows skin proximate the hole 144 (e.g., skinbeneath the concave depression 123) to be exposed to suction from theevacuated volume 141. This causes the skin 105 proximate the hole 144 tobe drawn up into the concave depression 123. Further, the skin 105 isdrawn up into the concave depression 123 such that the puncture 107 isaligned with the hole 144. This could facilitate the drawing of bloodfrom the skin 105 (e.g., from the puncture 107) through the hole 144into the device 100. In examples where skin is drawn, by suction, towarda device such that a formed puncture in the skin is not aligned with oneor more formed holes in a seal, blood could still be drawn into thedevice, e.g., due to wicking, surface tension, the blood filling thespace between the skin and device, or by some other mechanism.Properties of the spring 137, piston 130, needle 120, chamber 131,propellant 135, or other elements of the device 100 could be specifiedto maximize the speed with which the needle 120 is retracted from theskin 105 and/or minimize the duration during which the needle 120pierces the skin 105 to, e.g., reduce discomfort induced in a user byoperation of the device to penetrate the skin 105. Further, elements ofthe device 100 could be configured to minimize an amount of bloodemitted from the skin 105 that is deposited on the surface of the skin105 rather than being drawn and/or suctioned into the device 100 (e.g.,the device 100 could be configured to suction the skin 105 into contactwith the seal 143; the seal 143 could include a hydrophobic or othercoating to repel blood).

FIG. 2D shows blood 109 emitted from the skin 105 (e.g., from thepuncture 107 formed in the skin 105) that has been drawn through thehole 144 and into the device 100. Further, the emitted blood 109 hasbeen directed, via the channel 145, to the sensor 140. This couldinclude suction from the evacuated volume 141 drawing the blood 109through the channel 145 to the sensor 140. Additionally oralternatively, the blood 109 could be directed to and/or through thehole 144, through the channel 145, and/or to the sensor 140 byhydrophobic and/or hydrophilic coatings on one or more surfaces of theseal 143, channel 145, or other elements of the device 100. For example,a path from the hole 144 through the channel 145 to the sensor could becoated with a hydrophilic substance; other surfaces of the device 100that could come into contact with the blood 109 could be coated with ahydrophobic substance. Additionally or alternatively, the channel 145(or other elements of the device 100) could be sized to direct the blood109 using capillary action. The channel 145 or other elements of thedevice 100 could include a coating of heparin or some otherpharmaceutical to reduce coagulation and/or clotting of the blood 109 inthe device (e.g., to increase the duration and/or amount of blood 109flowing into the device 100 and/or to the sensor 140).

The shape, size, geometry, or other properties of the concave depression123 could be specified to maximize an amount of blood emitted from theskin 105 in response to being pierced by the needle 120. For example,the concave depression 123 could have a conical shape. The device 100could additionally or alternatively be configured in other ways tomaximize an amount of blood emitted from the skin 105. For example, thedevice 100 could be configured to increase blood flow in the skin 109proximate the device 100 and/or proximate the concave depression 123 by,e.g., heating the skin 105 before penetration, applying a frictive forceto the skin before penetration (e.g., by rubbing the skin), applyingsuction to the skin 105 before penetration, applying a vasodilating,anti-clotting, anti-coagulant, or other pharmaceutical (e.g., heparin,lidocaine) before, during, and/or after penetration of the skin 105, orby being configured or operated in some other way. Pharmaceuticals couldbe delivered as a coating on the needle 120. Additionally oralternatively, the needle 120 could be hollow and used to deliver apharmaceutical or other substance and/or to suction blood into thedevice 100 via such a hollow needle.

Further, the properties of the needle 120 could be specified to maximizethe amount of blood emitted from the skin 105, minimize discomfortinduced by penetration of the skin, or according to some otherconsideration. For example, the tip of the needle 120 could include atriple-bevel to minimize deflection of the skin 105 and/or to minimizeinduced discomfort due to piercing of the skin 105 by the needle 120.Alternatively, the needle 120 could have a chisel tip (e.g., a singlebevel), could have a flat ‘razor’ blade end, could include a taper(e.g., could become thinner toward the end), could be round, flat, orcould be configured in some other way to, e.g., maximize blood emittedfrom the skin 105. The needle 120 could be serrated. The diameter (orgauge) of the needle 120 could be specified to maximize the amount ofblood emitted from the skin 105 and/or to minimize discomfort induced bypiercing of the skin 105 by the needle 120. For example, the needle 120could have a gauge between approximately 21 gauge and approximately 36gauge.

In some examples, the piston 130 could drive multiple needles into theskin. FIG. 3 illustrates an example piston 330 that is coupled to threeparallel needles 320. The piston 330 additionally includes a piston vent333. A spacing between the needles 320, a number of the needles 320, thelengths and diameters of the needles 320, the geometry of the tips ofthe needles 320, or other properties of the needles 320 could bespecified to maximize the amount of blood emitted from skin pierced bythe needles 320 and/or to minimize discomfort induced by piercing of theskin by the needles 320. For example, the spacing between the needlescould be specified to maximize the likelihood of piercing at least oneblood vessel in the skin when the piston 330 drives the needles 320 intothe skin.

Further, the distance the needle 120 (or needles) pierces into the skin105 (related, e.g., to properties of the propellant 135, chamber 131,piston 130, spring 137, needle 120, and/or other elements of the device100) could be specified to maximize the amount of blood emitted from theskin 105 and/or to minimize discomfort induced by piercing of the skin105 by the needle 120. For example, the device 100 could be configuredsuch that the needle 120 penetrates skin 105 to a depth of approximately2 millimeters. In some examples, the device 100 could be configured suchthat the needle 120 penetrates skin 105 to a depth that containscapillaries and/or other blood vessels but that does not contain manynerve endings (e.g., to a depth near the transition between theepidermis and dermis layers of the skin 105). Additionally oralternatively, the device 100 could be configured to drive the needle120 into the skin 105 at a different angle than the one depicted (i.e.,an angle other than approximately 90 degrees).

The propellant 135 could include a variety of chemicals and combinationsof chemicals. For example, the propellant 135 could includenitrocellulose, butane, azide, or some other energetic gas-producingsubstance or other chemical(s). In some examples, the propellant couldbe formed and/or modified before use, e.g., the propellant could includeoxygen and hydrogen formed from water by electrolysis. Alternatively,the propellant could include a compressed gas (e.g., CO2, N2, aircompressed by a pump or other means, a goas generated by the device 100by electrolysis or some other method or means) to which the piston 130is exposed to drive the needle 120 into the skin 105. Additionally oralternatively, the piston 130 could be driven by a low pressure (e.g., avacuum, a suction source, an evacuated volume) beneath the piston 130.

The use of the resistive element 136 to ignite the propellant 135 isintended as a non-limiting example. Other means for igniting a chemicalpropellant (or some other chemical or element of the device 100according to an application) are anticipated, including but not limitedto generating an electrical spark (e.g., by applying a high voltageacross a spark gap or between electrodes of the device 100),illuminating the propellant (e.g., using a laser, an LED, or some otherlight-emitting element(s)), applying a fore and/or vibration to thepropellant (e.g., using a piezoelectric elements), or changing apressure to which the propellant is exposed. Further, the illustratedconfiguration of the piston 133 and chamber 132 vents are non-limitingexamples; more or fewer vents, vents located at different locations, orvents configured in some other way could be included to facilitate apiston driving a needle into skin and/or subsequently retracting theneedle from the skin. In an example, one or more of the vents could benormally closed and configured to open (either permanently ortemporarily) when a pressure across the vent exceeds some level (e.g.,when the pressure behind the piston 130 increases above a specifiedpressure due to ignition of the propellant 135). Additionally oralternatively, one or more vents could be located in the chamber 131such that gases behind the piston 130 (e.g., high-pressure gasesproduced by ignition of the propellant 135) are able to leave thechamber 131 through the vent only when the piston 130 is displaceddownward in the chamber 131 by some specified distance.

The piston 130, chamber 131, propellant 135, spring 137, and otherelements of the device 100 comprise an injector configured to drive theneedle 120 into skin and subsequently to retract the needle from theskin by igniting a chemical propellant. However, the device 100 couldinclude additional or alternative injectors configured to achievedriving of the needle 120 into skin and subsequent retraction thereof.In some examples, the injector could include one or more pre-loadedsprings configured to be released (e.g., by a manual button, by asolenoid or other electromechanical actuator). The injector couldinclude one or more magnets and/or cams configured to translate a forcebetween the one or more magnets and other elements of the device 100 toproduce driving and/or retracting force(s) that could be applied to theneedle 120. In some examples, the injector could include one or moremotors or other electromechanical actuator configured to apply drivingand/or retracting force(s) directly to the needle (e.g., through arack-and-pinion mechanism, using a cam, by applying magnetic forcesusing a solenoid) and/or by charging up a spring (e.g., a rotary spring)that could apply such force(s) to the needle 120. In some examples, theneedle 120 could be applied against the skin with a constant force thatis less than a force necessary to pierce the skin, and a vibrator (e.g.,a vibrating motor, a piezoelectric or otherwise configured ultrasonictransducer) could vibrate the needle 120 such that the needle 120pierces the skin. Other injectors or other means and methods for drivingthe needle 120 into the skin and subsequently retracting the needle areanticipated.

Suction applied to the seal 143 could be applied by a variety of meansor methods. As illustrated in FIGS. 1 and 2A-D, suction can be providedby an evacuated volume 141 that has a pressure that is lower than thepressure of the atmosphere surrounding the device 100. Additionally oralternatively, suction could be provided by a pump, a chemical processthat causes a decrease in pressure (e.g., by causing a decrease intemperature, by consuming nitrogen, oxygen, or some other gas from anenclosed volume (e.g., 141) and/or by changing a phase of such gases), aspring-loaded or otherwise actuated, enclosed volume that can beactuated to increase in size (thus producing suction), or by some othermeans of producing suction. In some examples, blood emitted from skin(e.g., due to penetration of the skin with a needle as described herein)could be drawn into the device 100, applied to a sensor (e.g., 140),stored, or otherwise manipulated according to an application withoutusing a source of suction, e.g., by using hydrophobic and/or hydrophiliccoatings and/or capillary forces to control the location and/or movementof blood within and/or relative to the device 100, by locating a sensor,blood storage element, or other element(s) of the device 100 proximateto the location at which the device 100 pierces the skin with the needle120, or by configuring the device 100 in some other way. In someexamples, e.g., when the needle 120 pierces a vein or other largervasculature, blood pressure or other forces within or beneath skin maycause a sufficient amount of blood to be emitted from the skin.

When suction is provided by a suction source that comprises an evacuatedvolume (e.g., 141), a pressure within the evacuated volume could bespecified to provide sufficient suction, for example, the pressurewithin the evacuated volume could be less than approximately 50kilopascals. Further, the device 100 could be constructed such that theevacuated volume has a pressure less than some maximum value (e.g., 50kilopascals) for some specified minimum period of time such that theevacuated volume could be used as a suction source to draw blood intothe device 100 at a specified future point in time. This could includethe device 100 include high-quality seals and adhesives between elementsof the device 100 that comprise and/or form the evacuated volume. Insome examples, surfaces elements (e.g., the housing 110, the seal 143,the circuit board 115) of the device 100 that are joined to form theevacuated volume could have highly smooth surfaces. In some examples,the device 100 could be configured and/or assembled such that thepressure within the evacuated volume remains below a specified maximumpressure for 48 hours, a week, or some other specified period of time topermit the use of the evacuated volume to provide suction to draw bloodinto the device 100 at a specified future point in time that is lessthan the specified period of time. In some examples, this could includestoring the device 100 in an evacuated volume of a package (e.g., withinan evacuated and sealed blister of packaging material) and removing thedevice 100 from the evacuated volume of the package before mounting thedevice 100 to skin.

The seal 143 could be composed of a variety of materials to allowsuction to be applied to and contained by the seal 143 until the seal ispierced by the needle 120. Further, the seal 143 could be composed ofmaterials that are capable of being vacuum-formed into a specified shape(e.g., a shape that can be mounted to the housing 110 and that includesone or more concave depressions, e.g., 123). For example, the seal 143could be composed of polycarbonate.

The sensor 140 could be configured to detect a variety of properties ofblood drawn into the device 100 (e.g., 109). For example, the sensor 140could be configured to detect the presence, concentration, or otherproperties of an analyte (e.g., glucose, small molecules, cells, cellcounts, hormones, cholesterol, testosterone, thyroid hormones, vitamins,minerals, electrolytes, cortisol, creatinine, luteinizing hormone,follicle stimulating hormone) in the blood. In some examples, the sensor140 could be configured to detect a clotting rate, viscosity,osmolarity, or other property of the blood. The sensor 140 could beconfigured to detect the property of the blood through direct contactbetween the blood and one or more elements of the sensor 140. Forexample, the sensor 140 could be an electrochemical sensor configured toamperometrically, potentiometrically, or otherwise electrochemicallydetect one or more properties of the blood when the blood comes intocontact with one or more electrodes of the electrochemical sensor (e.g.,when the blood comes into contact with a working electrode of the sensor140 that is selectively sensitive to an analyte of interest in the bloodand further comes into contact with a reference electrode of the sensor140). In another example, the sensor 140 could be configured to detect aproperty of the blood when the blood comes into contact with ananalyte-sensitive chemical (e.g., a fluorophore, a chromophore) that hasone or more optical properties (e.g., a color, a fluorescence intensity,a fluorescence lifetime) that are related to the analyte in the blood,and the sensor 140 could detect the analyte in the blood by opticallyinterrogating (e.g., illuminating and/or detecting light emitted from)the analyte-sensitive chemical. Additionally or alternatively, thesensor 140 could be configured to detect one or more properties of theblood without being in direct contact with the blood, e.g., by detectinga color of the blood, a property of motion of the blood, or some otherproperty.

Additionally or alternatively, a device as described herein could beconfigured to store blood emitted and/or drawn from skin (e.g., for somelater analysis). FIG. 4 shows a cross-sectional view of a device 400that is configured to be mounted to skin, to pierce the skin with aneedle 420, to retract the needle, and to draw blood from the skin intothe device 400 and to store the blood in a blood storage element 440.The needle 420 additionally acts to pierce a seal 443 such that suctionprovided by the device (e.g., by an evacuated volume 441 of the device)can be applied through a formed hole in the seal 443 to draw blood fromthe skin through the formed hole in the seal 443 and into the bloodstorage element 440. In the illustrated example, the blood storageelement 440 includes a capillary tube, but a blood storage element of adevice could additionally or alternatively include an ampoule, a basin,a pit, or some other geometry configured to contain blood. Further, ablood storage element (e.g., 440) could be configured to preserve,chemically modify, prevent clotting or coagulation of, or otherwisemanipulate the stored blood. For example, the blood storage element 440could contain heparin to prevent clotting and/or coagulation of drawn,stored blood. Alternatively, the blood storage element could beconfigured to allow the blood to dry, according to an application. Insome examples, the blood storage element could include an absorptivematerial, e.g., a piece of fabric configured to absorb blood or otherfluids.

Stored blood could be presented to a sensor or other element(s) of asensing device (e.g., a desktop or other device separate from ablood-accessing device as described herein, e.g., 100, 400) configuredto detect one or more properties of the stored blood. For example, ablood accessing device could be configured to be mounted to such asensing device and to provide the stored blood to the sensing device.This could include the sensing device detecting one or more propertiesof the stored blood while it remains in the blood-accessing device(e.g., by optically detecting a property of the stored blood byilluminating and/or receiving light from the stored blood through awindow, an optical fiber, or other optically transparent elements of theblood-accessing device). Additionally or alternatively, theblood-accessing device providing the stored blood to a sensing devicecould include the stored blood being removed from a blood storageelement or other components of the blood-accessing device.

A blood-accessing device or system as described herein (e.g., 100, 400)could include multiple sensors, blood-storage elements, needles,injectors, seals, and/or other elements. As illustrated in FIG. 1A,device 100 includes six sections, each section including a respectiveneedle, injector, suction source, and other elements. Each section isconfigured to drive its respective needle into skin, to subsequentlyretract the needle from the skin, and the receive blood emitted from theskin in response to being penetrated by the needle. Each section couldinclude one or more sensors, one or more blood storage elements, and/oradditional components configured to receive, transmit, measure, modify,or otherwise interact with blood received from the skin. The sections ofa device could be similarly configured (e.g., could include similarsensors, be configured to draw similar amounts of blood from skin in asimilar manner) or could be differently configured (e.g., differentsensors, differently configured injectors, differently configuredneedles). The sections of a device could be operated to access bloodfrom skin at respective different points in time, e.g., at a number ofpoints in time while a wearer of the device is asleep, at a number ofpoints in time during a week, in response to a command received from auser and/or from a remote system in communication (e.g., wirelesscommunication via Bluetooth, ZigBee, WiFi, or some other wirelesscommunications protocol), in response to a detected command (e.g., abutton press) and/or behavior (e.g., performance of an exerting athleticactivity, detected using, e.g., an accelerometer of the device 100) of awearer, based on a detected physiological state of the wearer (e.g., aheart rate or blood pressure detected by sensor(s) of the device 100),or according to some other scheme.

Further, a device could include more or fewer sections, organizedsimilarly or differently (e.g., in a row, rather than circularly asillustrated) than those embodiments illustrated herein. For example, ablood-accessing device could include a single section. In exampleswherein the injector and/or suction source are single-use (e.g., whereinthe injector ignites a limited supply of a propellant and/or whereinsuction is provided by a single evacuated volume) and the deviceincludes a single such section, the blood-accessing device could beconfigured for a single use. In some examples, such a single and/orlimited-use (e.g., six uses, as illustrated in FIG. 1A) could beconfigured to be a removable and/or replaceable element of some otherdevice. For example, the blood-accessing device 100 could be configuredto be removably mounted on or within a body-mountable device (e.g., awrist-mountable device) that includes a controller, a user interface, abattery, a communications interface, or some other elements. Such abody-mountable device could be configured to operate the limited-useblood-accessing device to access a number of samples of blood from skin(e.g., at respective specified points in time). Once the body-mountabledevice has operated all of the limited-use sections of theblood-accessing device, the blood-accessing device could be removed fromthe body-mountable device and replaced. In some examples, the removedblood-accessing device could be configured to store blood, and bloodstored in the removed blood-accessing device could be presented to asensing device for analysis (e.g., the removed blood-accessing devicecould be sent via post to a sensing device at a laboratory that isremote from a user of the body-mountable device).

Note that the configurations and operations of devices as describedherein are meant as non-limiting examples of operation of devicesconfigured to puncture skin and to receive blood emitted from the skinin response to being punctured. Such devices could include a variety ofmeans for penetrating or piercing skin, for driving such penetratingmeans into skin, for subsequently retracting such penetrating means fromthe skin, for drawing, wicking, suctioning, or otherwise receiving bloodresponsively emitted from the skin, for storing the received blood, forsensing one or more properties of the received blood, for moving,directing, preserving, or otherwise interacting with the received blood,or for performing some additional or alternative operations of functionsaccording to an application.

III. EXAMPLE WEARABLE DEVICES

Wearable blood-accessing devices as described herein can be configuredto be mounted to an external body surface of a wearer and to enable avariety of applications and functions including accessing blood of thewearer (e.g., drawing, extracting, or otherwise receiving blood),storing such accessed blood, detecting one or more properties of suchaccessed blood, detecting some other properties of the body of thewearer (e.g., a pulse rate), or performing some other functions. Suchwearable devices could enable a variety of applications, includingmeasuring homological properties or other physiological informationabout a wearer, indicating such measured information or otherinformation to the wearer (e.g., using a vibrator, a screen, a beeper),recording such information, indicating such information to a remotesystem (e.g., a server in a physician's office), or other functions.

In some examples, a wearable device 500 (illustrated in FIG. 5) isprovided as a wrist-mounted device, as shown in FIGS. 5A and 5B. Thewrist-mounted device 500 may be mounted to the wrist of a living subjectwith a wristband or cuff, similar to a watch or bracelet. The wearabledevice 500 can be configured to access blood of a wearer and to store,detect a property of, or otherwise interact with such accessed blood.The term “wearable device,” as used in this disclosure, refers to anydevice that is capable of being worn at, on or in proximity to a bodysurface, such as a wrist, ankle, waist, chest, or other body part. Inorder to access blood from within and/or beneath skin of the body, thewearable device may be positioned on a portion of the body wheresubsurface vasculature or other targets or elements of the body of thewearer are easily accessed (e.g., punctured), the qualification of whichwill depend on the type of system used. A mount 510, such as a belt,wristband, ankle band, etc. can be provided to mount the device at, onor in proximity to the body surface. The mount 510 may prevent thewearable device from moving relative to the body to allow for blood tobe drawn from a puncture produced in the skin by the device 500 (e.g.,by a driven and subsequently retracted needle of the device) oraccording to some other application or consideration. In one example,shown in FIGS. 5A and B, the mount 510 may take the form of a strap orband 520 that can be worn around the wrist (or some other part) of thebody. Further, the mount 510 may be an adhesive substrate for adheringthe blood-accessing device 500 to the body of a wearer.

A housing 530 is disposed on the mount 510 such that it can bepositioned on the body. A contact surface 540 of the housing 530 isintended to be mounted facing to the external body surface. The housing530 may include sensors for detecting one or more physiologicalproperties of the wearer (e.g., a pulse, a blood oxygenation, a galvanicskin response). The contact surface 540 additionally includes a numberof concave depressions 550. Each concave depression 550 corresponds to ablood-accessing section of the device 500 that can be operated to drivea needle, through the concave depression (e.g., through a seal of thedevice and/or through a channel of the device configured to allow thepassage of the needle), into skin of a wearer and subsequently toretract the needle from the skin. Further, each section is configured toreceive blood responsively emitted from the skin (e.g., by wicking,capillary action, application of suction, or some other means) and tostore, detect a property of, or otherwise interact with the receivedblood.

The housing 530 could be configured to be water-resistant and/orwater-proof. That is, the housing 530 could be configured to includesealants, adhesives, gaskets, welds, transparent windows, apertures,press-fitted seams, and/or other joints such that the housing 530 isresistant to water entering an internal volume or volumes of the housing530 when the housing 530 is exposed to water. The housing 530 couldfurther be water-proof, i.e., resistant to water entering an internalvolume or volumes of the housing 530 when the housing 530 is submergedin water. For example, the housing 530 could be water-proof to a depthof 1 meter, i.e., configured to resist water entering an internal volumeor volumes of the housing 530 when the housing 530 is submerged to adepth of 1 meter.

The wearable device 500 may also include a user interface 590 via whichthe wearer of the device may receive one or more recommendations oralerts generated either from a remote server or other remote computingdevice, or from a processor within the device. The alerts could be anyindication that can be noticed by the person wearing the wearable device500. For example, the alert could include a visual component (e.g.,textual or graphical information on a display), an auditory component(e.g., an alarm sound), and/or tactile component (e.g., a vibration).Further, the user interface 590 may include a display 592 where a visualindication of the alert or recommendation may be displayed. The display592 may further be configured to provide an indication of a measuredhemodynamic property of blood accessed from the body of the wearer usingthe device (e.g., to provide an indication of a blood glucose level ofthe wearer's blood).

Further, the user interface 590 may include one or more buttons 594 foraccepting inputs from the wearer. For example, the buttons 594 may beconfigured to change the text or other information visible on thedisplay 592. The buttons 594 may be configured to accept inputs forcontrolling aspects of the data collection system, such as initiating ameasurement period (e.g., causing the device 500 to access blood of thewearer by driving a needle into skin or according to some other method),inputs indicating the wearer's current health state (i.e., normal,migraine, shortness of breath, heart attack, fever, “flu-like” symptoms,food poisoning, etc.), or inputs indicating the wearer's activities(e.g., eating a meal, taking a medication).

Note that example devices herein are configured to be mounted to a wristof a wearer. However, the embodiments described herein could be appliedto other body parts (e.g., an ankle, a thigh, a chest, an abdomen, aforehead, a thigh, a finger), or to detect hematological properties orother physiological properties in other environments. For example,embodiments described herein could be applied to detect one or moreproperties in a target environment (e.g., a natural environment, anenvironment of an industrial, pharmaceutical, or water treatmentprocess).

Blood-accessing sections of the device 500 could be single-use; forexample, an injector of one or more sections could ignite a limitedsupply of a propellant and/or wherein suction is provided for/in asection by a single evacuated volume. In such examples, such singleand/or limited-use blood-accessing sections could be configured to be aremovable and/or replaceable element of the wearable device 500. Forexample, FIGS. 6A and 6B show a blood-accessing device 600 that could beconfigured to be removably mounted on or within the wearable device 500.The blood-accessing device 600 includes a housing 610 that can bepositioned on skin of a body when the blood-accessing device 600 ismounted on or within the wearable device 500 and the wearable device 500is mounted to the body. A contact surface 605 of the housing 610 isintended to be mounted facing to the external body surface. The contactsurface 605 includes a number of concave depressions 620. Each concavedepression 620 corresponds to a blood-accessing section of theblood-accessing device 600 that can be operated (e.g., when mounted onor within the wearable device 500) to drive a needle, through theconcave depression (e.g., through a seal of the device and/or through achannel of the device configured to allow the passage of the needle),into skin of a wearer and subsequently to retract the needle from theskin. Further, each section is configured to receive blood responsivelyemitted from the skin (e.g., by wicking, capillary action, applicationof suction, or some other means) and to store, detect a property of, orotherwise interact with the received blood.

The wearable device 500 could be configured to operate theblood-accessing device 600 to access a number of samples of blood fromskin (e.g., at respective specified points in time). Once thebody-mountable device has operated all of the sections of theblood-accessing device 600, the blood-accessing device 600 could beremoved from the wearable device 500 and replaced. In some examples,this could include operating one or more injectors, suction sources,and/or other components of the blood-accessing device 600 (e.g., viaelectrical connector 640, optical receiver/transmitter 645, and/orelectronics 630). Additionally or alternatively, the wearable device 500could operate the blood-accessing device 600 using other means, e.g., byigniting propellant of the blood-accessing device 600 by heating thepropellant using a laser of the wearable device 500.

In some examples, the removed blood-accessing device 600 could beconfigured to store blood, and blood stored in the removedblood-accessing device 600 could be presented to a sensing device foranalysis (e.g., the removed blood-accessing device 600 could be sent viapost to a sensing device at a laboratory that is remote from a user ofthe body-mountable device 500). For example, samples of blood storedwithin the blood-accessing device 600 could be accessed via ports 650 ofthe blood-accessing device 600.

Additionally or alternatively, the wearable device 500 could beconfigured to detect one or more properties of the blood accessed usingthe blood-accessing device 600. In some examples, the blood-accessingdevice 600 could include one or more sensors configured to detect one ormore properties of blood. The wearable device 500 could operate thesensors of the blood-accessing device 600 (e.g., via electricalconnector 640, optical receiver/transmitter 645, and/or electronics 630.Additionally or alternatively, the wearable device 500 could beconfigured to illuminate and/or receive light emitted from theblood-accessing device 600 (e.g., to illuminate and/or receive lightemitted from an analyte-sensitive chemical that has one or more opticalproperties that is related to the analyte in the blood), via a window,optical fiber, or other optically transparent element(s) of theblood-accessing device 600) to detect one or more properties of theblood drawn, wicked, suctioned, or otherwise received from skin by theblood-accessing device 600.

Wearable blood-accessing devices and other embodiments as describedherein can include a variety of components configured in a variety ofways. Devices described herein could include electronics including avariety of different components configured in a variety of ways toenable applications of the wearable device. The electronics couldinclude controllers, amplifiers, switches, display drivers, touchsensors, wireless communications chipsets (e.g., Bluetooth radios orother radio transceivers and associated baseband circuitry to enablewireless communications between the wearable device and some othersystem(s)), or other components. The electronics could include acontroller configured to operate one or more sensors, injectors, suctionsources, and/or components of a blood-accessing device to detect one ormore hematological or other properties of a body and/or to access andstore or otherwise interact with blood from within and/or beneath skinof the body. The controller could include a processor configured toexecute computer-readable instructions (e.g., program instructionsstored in data storage of the wearable device) to enable applications ofthe wearable device. The electronics can include additional oralternative components according to an application of the wearabledevice.

Wearable or otherwise-configured blood-accessing devices as describedherein could include one or more user interfaces. A user interface couldinclude a display configured to present an image to a wearer and todetect one or more finger presses of a wearer on the interface. Thecontroller or some other component(s) of the electronics could operatethe user interface to provide information to a wearer or other user ofthe device and to enable the wearer or other user to affect theoperation of the wearable device, to determine some property of thewearable device and/or of the wearer of the wearable device (e.g., ahematological property of blood and/or a health state of a wearer of thewearable device), or to provide some other functionality or applicationto the wearer and/or user. As one example, the wearer could press anindicated region of the user interface to indicate that the wearabledevice should begin logging detected medical information about thewearer. Other indicated information, changes in operation of thewearable device, or other functions and applications of the userinterface are anticipated.

Note that the embodiments illustrated in the Figures are illustrativeexamples and not meant to be limiting. Alternative embodiments,including more or fewer components in alternative configurations areanticipated. A wearable, handheld, body-mountable, desktop, or otherwiseconfigured device could include multiple housings or other suchassemblies each containing some set of components to enable applicationsof such a device. A blood-accessing device as described herein could beconfigured to perform a variety of functions and to enable a variety ofapplications. Blood-accessing devices could be configured to operate inconcert with other devices or systems; for example, blood-accessingdevices could include a wireless communication interface configured totransmit data indicative of one or more properties of the blood of awearer of the wearable device. Other embodiments, operations,configurations, and applications of a blood-accessing device asdescribed herein are anticipated.

FIG. 7 is a simplified schematic of a system including one or morewearable blood-accessing devices 700. The one or more wearable devices700 may be configured to transmit data via a communication interface 710over one or more communication networks 720 to a remote server 730. Inone embodiment, the communication interface 710 includes a wirelesstransceiver for sending and receiving communications to and from theserver 730. In further embodiments, the communication interface 710 mayinclude any means for the transfer of data, including both wired andwireless communications. For example, the communication interface mayinclude a universal serial bus (USB) interface or a secure digital (SD)card interface. Communication networks 720 may be any one of may be oneof: a plain old telephone service (POTS) network, a cellular network, afiber network and a data network. The server 730 may include any type ofremote computing device or remote cloud computing network. Further,communication network 720 may include one or more intermediaries,including, for example wherein the wearable device 700 transmits data toa mobile phone or other personal computing device, which in turntransmits the data to the server 730.

In some examples, multiple wearable devices 700 could be configured toaccess blood from and/or detect multiple hematological or otherproperties of a single wearer. For example, the single wearer could wearor otherwise operate two or more wearable devices 700 to measurerespective hematological or other physiological properties fromrespective two or more portions of the body of the wearer (e.g.,respective portions of subsurface vasculature of the wearer) and/orduring different periods of time (e.g., the wearable devices 700 used bythe wearer could be limited-use devices, e.g., each including a discretenumber of single-use blood-accessing sections).

In addition to receiving communications from the wearable device 700,such as collected hematological properties or other collectedphysiological properties and data regarding health state as input by theuser and/or one or more properties of a wearer detected using a sensordisposed in the wearable device 700, the server may also be configuredto gather and/or receive either from the wearable device 700 or fromsome other source, information regarding a wearer's overall medicalhistory, environmental factors and geographical data. For example, auser account may be established on the server for every wearer thatcontains the wearer's medical history. Moreover, in some examples, theserver 730 may be configured to regularly receive information fromsources of environmental data, such as viral illness or food poisoningoutbreak data from the Centers for Disease Control (CDC) and weather,pollution and allergen data from the National Weather Service. Further,the server may be configured to receive data regarding a wearer's healthstate from a hospital or physician. Such information may be used in theserver's decision-making process, such as recognizing correlations andin generating clinical protocols.

Additionally, the server may be configured to gather and/or receive thedate, time of day and geographical location of each wearer of the deviceduring each measurement period. Such information may be used to detectand monitor spatial and temporal spreading of diseases. As such, thewearable device may be configured to determine and/or provide anindication of its own location. For example, a wearable device mayinclude a GPS system so that it can include GPS location information(e.g., GPS coordinates) in a communication to the server. As anotherexample, a wearable device may use a technique that involvestriangulation (e.g., between base stations in a cellular network) todetermine its location. Other location-determination techniques are alsopossible.

The server may also be configured to make determinations regarding theefficacy of a drug or other treatment based on information regarding thedrugs or other treatments received by a wearer of the device and, atleast in part, the hematological property data and the indicated healthstate of the user. From this information, the server may be configuredto derive an indication of the effectiveness of the drug or treatment.For example, if a drug is intended to control a blood sugar of a wearerand the wearer of the device does not indicate that they areexperiencing nausea, lightheadedness, or other sequelae after beginninga course of treatment with the drug, the server may be configured toderive an indication that the drug is effective for that wearer.

Further, some embodiments of the system may include privacy controlswhich may be automatically implemented or controlled by the wearer ofthe device. For example, where a wearer's collected hematologicalproperty data and health state data are uploaded to a cloud computingnetwork for trend analysis by a clinician, the data may be treated inone or more ways before it is stored or used, so that personallyidentifiable information is removed. For example, a user's identity maybe treated so that no personally identifiable information can bedetermined for the user, or a user's geographic location may begeneralized where location information is obtained (such as to a city,ZIP code, or state level), so that a particular location of a usercannot be determined.

Additionally or alternatively, wearers of a device may be provided withan opportunity to control whether or how the device collects informationabout the wearer (e.g., information about a user's medical history,social actions or activities, profession, a user's preferences, or auser's current location), or to control how such information may beused. Thus, the wearer may have control over how information iscollected about him or her and used by a clinician or physician or otheruser of the data. For example, a wearer may elect that data, such ashealth state and hematological properties, collected from his or herdevice may only be used for generating an individual baseline andrecommendations in response to collection and comparison of his or herown data and may not be used in generating a population baseline or foruse in population correlation studies.

IV. EXAMPLE ELECTRONICS

FIG. 8 is a simplified block diagram illustrating the components of adevice 800, according to an example embodiment. Device 800 may take theform of or be similar to one of the blood-accessing devices 100, 400,500, 600 shown in FIGS. 1, 2A-D, 4, 5A-B, and 6A-B. However, device 800may also take other forms, such as an ankle, waist, or chest-mounteddevice. Device 800 could also take the form of a device that is notconfigured to be mounted to a body. For example, device 800 could takethe form of a handheld device configured to be maintained in proximityto skin by a user or operator of the device 800 or by a frame or othersupporting structure. Device 800 also could take other forms.

In particular, FIG. 8 shows an example of a device 800 having first 810and second 820 blood-accessing sections, a user interface 830,communication interface 835 for transmitting data to a remote system,and a controller 840. The components of the device 800 may be disposedon a mount or on some other structure for mounting the device to enablestable collection of blood emitted from skin in response to penetrationof the skin by one or more needles of the device 800, for example,mounting to an external body surface where one or more portions ofsubsurface vasculature or other anatomical elements are readilyaccessible.

Controller 840 may be provided as a computing device that includes oneor more processors 850. The one or more processors 850 can be configuredto execute computer-readable program instructions 870 that are stored inthe computer readable data storage 860 and that are executable toprovide the functionality of a device 800 described herein.

The computer readable medium 860 may include or take the form of one ormore non-transitory, computer-readable storage media that can be read oraccessed by at least one processor 850. The one or morecomputer-readable storage media can include volatile and/or non-volatilestorage components, such as optical, magnetic, organic or other memoryor disc storage, which can be integrated in whole or in part with atleast one of the one or more processors 850. In some embodiments, thecomputer readable medium 860 can be implemented using a single physicaldevice (e.g., one optical, magnetic, organic or other memory or discstorage unit), while in other embodiments, the computer readable medium860 can be implemented using two or more physical devices.

First 810 and second 820 blood-accessing sections could include anycomponents configured to drive a needle into skin, to subsequentlyretract the needle from the skin, to receive blood from the resultingpuncture in the skin (e.g., by applying suction to the skin), and toperform other functions as described elsewhere herein. Blood-accessingsections could include motors, piezoelectric transducers, solenoids,actuated valves, resistive heaters or other propellant-ignitingcomponents, or other components of an injector configured to drive aneedle into skin and/or to subsequently retract such a needle.Blood-accessing sections 810, 820 could include blood-storage elementsas described elsewhere herein to store blood for, e.g., later analysis.Blood-accessing sections 810, 820 could include sensors configured todetect a variety of properties of blood drawn, wicked, suctioned,received, or otherwise accessed by the blood-accessing sections 810,820. Blood-accessing sections 810, 820 could include pumps of otherelements (e.g., evacuated volumes) configured to provide suction (e.g.,to draw skin toward and/or into concave depressions of theblood-accessing sections 810, 820, to draw blood from the skin into thedevice 800, to direct blood from within the device, 800, e.g., to one ormore sensors, blood-storage elements, or other components of the device800). The device 800 could include additional (or fewer) blood-accessingsections. The blood-accessing sections 810, 820 could be similarly ordifferently configured. The blood-accessing sections 810, 820 could bepart of a removable and/or replaceable portion of the device 800. Thedevice 800 may include further sensors (not shown), e.g., heart ratesensors, galvanic skin response sensors, pulse oximeters, or othersensors configured to detect one or more properties of the body of awearer and/or of the environment of the device 800.

The program instructions 870 stored on the computer readable medium 860may include instructions to perform any of the methods described herein.For instance, in the illustrated embodiment, program instructions 870include a controller module 872, calculation and decision module 874 andan alert module 876.

Calculation and decision module 874 may include instructions foroperating the blood-accessing sections 810, 820 and analyzing datagenerated by the blood-accessing sections 810, 820 (e.g., by sensorsthereof) to determine one or more hematological properties of blood orother information (e.g., health states) of a body of a wearer of thedevice 800, such as a blood glucose level at a number of points in time.Calculation and decision module 874 can additionally includeinstructions for analyzing the data to determine if a medical conditionor other specified condition is indicated, or other analytical processesrelating to the environment proximate to the device 800 (e.g., based oninformation generated by additional sensors of the device 800). Inparticular, the calculation and decision module 874 may includeinstructions for operating the first 810 and second 820 blood-accessingsections to access blood (e.g., for operating resistive heating elementsof the blood-accessing sections 810, 820 to ignite propellant and driverespective needles into skin) at respective specified points in time(e.g., points in time while a wearer sleeps, points in time during theweek).

The controller module 872 can also include instructions for operating auser interface 830. For example, controller module 872 may includeinstructions for displaying data collected by the blood-accessingsections 810, 820 and analyzed by the calculation and decision module874, or for displaying one or more alerts generated by the alert module876. Controller module 872 may include instructions for displaying datarelated to a detected hematological property of accessed blood and/or adetermined health state of a wearer. Further, controller module 872 mayinclude instructions to execute certain functions based on inputsaccepted by the user interface 830, such as inputs accepted by one ormore buttons disposed on the user interface (e.g., to operate one orboth of the blood-accessing sections 810, 820 to access blood from awearer and/or to detect one or more properties of the accessed blood inresponse to an input from the user).

Communication platform 835 may also be operated by instructions withinthe controller module 872, such as instructions for sending and/orreceiving information via a wireless antenna, which may be disposed onor in the device 800. The communication interface 835 can optionallyinclude one or more oscillators, mixers, frequency injectors, etc. tomodulate and/or demodulate information on a carrier frequency to betransmitted and/or received by the antenna. In some examples, the device800 is configured to indicate an output from the processor by modulatingan impedance of the antenna in a manner that is perceivable by a remoteserver or other remote computing device.

The program instructions of the calculation and decision module 874 may,in some examples, be stored in a computer-readable medium and executedby a processor located external to the device 800. For example, thedevice 800 could be configured to collect certain data regardinghematological properties from the user and then transmit the data to aremote server, which may include a mobile device, a personal computer,the cloud, or any other remote system, for further processing.

The computer readable medium 860 may further contain other data orinformation, such as medical and health history of a user of the device800, that may be useful in determining whether a medical condition orsome other specified condition is indicated. Further, the computerreadable medium 860 may contain data corresponding to certainphysiological parameter baselines, above or below which a medicalcondition is indicated. The baselines may be pre-stored on the computerreadable medium 860, may be transmitted from a remote source, such as aremote server, or may be generated by the calculation and decisionmodule 874 itself. The calculation and decision module 874 may includeinstructions for generating individual baselines for the user of thedevice 800 based on data collected based on a certain number of bloodsamples accessed using blood-accessing elements (e.g., 810, 820) of thedevice 800. Baselines may also be generated by a remote server andtransmitted to the device 800 via communication interface 830. Thecalculation and decision module 874 may also, upon determining that amedical or other emergency condition is indicated, generate one or morerecommendations for the user of the device 800 based, at least in part,on consultation of a clinical protocol. Such recommendations mayalternatively be generated by the remote server and transmitted to thedevice 800.

In some examples, the collected hematological property data, baselineprofiles, health state information input by device users and generatedrecommendations and clinical protocols may additionally be input to acloud network and be made available for download by a user's physician.Trend and other analyses may also be performed on the collected data,such as hemodynamic property data and health state information, in thecloud computing network and be made available for download by physiciansor clinicians.

Further, hematological property and health state data from individualsor populations of device users may be used by physicians or cliniciansin monitoring efficacy of a drug or other treatment. For example,high-density, real-time data may be collected from a population ofdevice users who are participating in a clinical study to assess thesafety and efficacy of a developmental drug or therapy. Such data mayalso be used on an individual level to assess a particular wearer'sresponse to a drug or therapy. Based on this data, a physician orclinician may be able to tailor a drug treatment to suit an individual'sneeds.

In response to a determination by the calculation and decision module874 that a medical or other specified condition is indicated (e.g., thata wearer is hyperglycemic or hypoglycemic, based on a detected glucoselevel of blood accessed from the body of the wearer), the alert module876 may generate an alert via the user interface 830. The alert mayinclude a visual component, such as textual or graphical informationdisplayed on a display, an auditory component (e.g., an alarm sound),and/or tactile component (e.g., a vibration). The textual informationmay include one or more recommendations, such as a recommendation thatthe user of the device contact a medical professional, deliver a dose ofa pharmaceutical (e.g., insulin), seek immediate medical attention, oradminister a medication.

V. EXAMPLE METHODS

FIG. 9 is a flowchart of a method 900 for operating a blood-accessingsystem.

The operated system includes: (i) a needle configured to penetrate skin,(ii) an injector, (iii) a suction source, and (iv) a seal configured toreceive suction provided by the suction source. The method 900 includesmounting the system to skin (910). The system could be a wearable deviceand mounting the system to skin (910) could include mounting the systemto and/or around a part of a body using a strap, adhesive, or some othermeans. The system could be a handheld device and mounting the system toskin (910) could include manually or otherwise positioning the systemproximate skin. The system could be a desktop device, a wall- orceiling-mounted device, or some other form of stationary device andmounting the system to skin (910) could include positioning a body parthaving the skin (e.g., a wrist, and arm) proximate the system.

The method 900 also includes operating the injector to drive the needleinto the skin through the seal and subsequently to retract the needle toform at least one hole in the seal through which the suction source candraw blood (920). This could include operating the injector at aspecified point in time and/or in response to a command (e.g., a commandreceived through a user interface of the system, a command generated bythe system in reasons to detecting that skin is present proximate thesystem, a command generated by a remote system in communication with theblood-accessing system). Operating the injector (920) could includeigniting a propellant, e.g., by heating the propellant using a resistiveheating element. Additionally or alternatively, operating the injector(920) could include operating a motor, solenoid, piezoelectrictransducer, or other elements of the system and/or of the injector.

The system could include one or more sensors configured to detect one ormore properties of blood accessed by the system and the method 900 couldinclude operating the sensor to detect the one or more properties of theblood (e.g., to detect a glucose concentration in the blood).Additionally or alternatively, the system could include one or moreblood storage elements configured to receive and store blood accessed bythe system and the method 900 could include storing the accessed blood.The method 900 could further include providing blood stored by the bloodstorage element to a sensing device and operating the sensing device todetect a property of the blood provided to the sensing device. In someexamples, one or more elements, sections, or portions of the system(e.g., a section configured to drive a needle into skin, subsequentlyretract the needle, and to apply suction to the skin to draw blood intothe section) could be removable, and the method 900 could includeremoving and replacing such elements, sections, or portions subsequentto operating such elements, sections, or portions to access blood fromskin.

The method 900 could include additional or alternative steps. The method900 could include heating, applying suction to, or otherwise preparing aportion of skin to emit blood in response to being pierced by a needleof the system. In some examples, the method 900 could includetransmitting (e.g., wirelessly transmitting, transmitting via aBluetooth wireless link, transmitting via a cable, transmitting via theinternet or some other network) information indicative of a detectedhematological property of blood accessed by the system. In someexamples, the method 900 could include determining a health state of thewearer based on a hematological property detected from blood accessed bythe system. In some examples, the method 900 could include indicating adetected hematological properties to a user via a user interface of thesystem and/or indicating such information to a remote system (e.g., to aphysician's computer, via a wireless or other communications link).

The example method 900 illustrated in FIG. 9 is meant as anillustrative, non-limiting example. Additional or alternative elementsof the method and additional or alternative components of the system areanticipated, as will be obvious to one skilled in the art.

VI. CONCLUSION

Where example embodiments involve information related to a person or adevice of a person, the embodiments should be understood to includeprivacy controls. Such privacy controls include, at least, anonymizationof device identifiers, transparency and user controls, includingfunctionality that would enable users to modify or delete informationrelating to the user's use of a product.

Further, in situations in where embodiments discussed herein collectpersonal information about users, or may make use of personalinformation, the users may be provided with an opportunity to controlwhether programs or features collect user information (e.g., informationabout a user's medical history, social network, social actions oractivities, profession, a user's preferences, or a user's currentlocation), or to control whether and/or how to receive content from thecontent server that may be more relevant to the user. In addition,certain data may be treated in one or more ways before it is stored orused, so that personally identifiable information is removed. Forexample, a user's identity may be treated so that no personallyidentifiable information can be determined for the user, or a user'sgeographic location may be generalized where location information isobtained (such as to a city, ZIP code, or state level), so that aparticular location of a user cannot be determined. Thus, the user mayhave control over how information is collected about the user and usedby a content server.

The particular arrangements shown in the Figures should not be viewed aslimiting. It should be understood that other embodiments may includemore or less of each element shown in a given Figure. Further, some ofthe illustrated elements may be combined or omitted. Yet further, anexemplary embodiment may include elements that are not illustrated inthe Figures.

Additionally, while various aspects and embodiments have been disclosedherein, other aspects and embodiments will be apparent to those skilledin the art. The various aspects and embodiments disclosed herein are forpurposes of illustration and are not intended to be limiting, with thetrue scope and spirit being indicated by the following claims. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which arecontemplated herein.

What is claimed is:
 1. A system comprising: a needle, wherein the needle is configured to penetrate skin; an injector, wherein the injector is configured to drive the needle into the skin to form a puncture in the skin and subsequently to retract the needle from the skin; a sensor, wherein the sensor is configured to detect a property of blood to which the sensor is exposed; and a controller configured to: operate the injector to drive the needle into the skin; and subsequent to operating the injector to drive the needle into the skin, operate the sensor to detect a property of blood received from the skin in response to the needle being driven into the skin.
 2. The system of claim 1, wherein the system comprises a body-mountable device, wherein the body-mountable device is configured to be mounted to a surface of the skin, and wherein the controller is configured to operate the injector to drive the needle into the skin at a specified point in time.
 3. The system of claim 2, wherein the needle, injector, and sensor are disposed in a first sampling section of the body-mountable device, and wherein the body-mountable device further comprises one or more additional sampling sections, each additional sampling section including a respective needle, injector, and sensor.
 4. The system of claim 3, wherein the controller is configured to operate an injector of a particular additional sampling section to drive a needle of the additional sampling section into the skin at a further specified point in time.
 5. The system of claim 1, wherein the injector comprises: a chamber, wherein the needle is disposed at least partially within the chamber; a piston disposed in the chamber, wherein the needle is coupled to the piston, and wherein the piston is configured to slidably move within the chamber; and a propellant, wherein the propellant is configured to slidably move the piston within the chamber to drive the needle into skin.
 6. The system of claim 5, wherein the propellant comprises nitrocellulose, and wherein the injector driving the needle into skin comprises the injector igniting the nitrocellulose.
 7. The system of claim 5, wherein the injector driving the needle into skin comprises the injector igniting the propellant using a resistive heating element.
 8. The system of claim 5, wherein the injector includes at least one vent, wherein the vent is configured to allow the propellant to vent out of the injector such that the piston and needle can retract from the skin subsequent to the needle being driven into the skin.
 9. The system of claim 1, further comprising: a suction source configured to provide suction; and a seal, wherein the seal is configured to receive suction provided by the suction source, wherein the injector is configured to drive the needle through the seal to form at least one hole in the seal, and wherein the suction provided by the suction source is configured to draw blood from the formed puncture in the skin through the formed at least one hole in the seal.
 10. The system of claim 9, further comprising at least one further needle, wherein the injector is configured to drive the at least one further needle into the skin to form at least one further puncture in the skin and subsequently to retract the at least one further needle from the skin, and wherein the injector is configured to drive the at least one further needle through the seal to form at least one further hole in the seal.
 11. The system of claim 9, wherein the seal comprises a concave depression, wherein the injector is configured to drive the needle through the concave depression of the seal to form at least one hole in the seal, and wherein the suction provided by the suction source is configured to suction the skin into the concave depression.
 12. The system of claim 9, wherein the suction source comprises an evacuated volume having a pressure less than approximately 50 kilopascal.
 13. The system of claim 9, further comprising a blood storage element, wherein the suction provided by the suction source is configured to draw blood through the formed at least one hole in the seal to the blood storage element, and wherein the blood storage element is configured to store blood drawn by the suction to the blood storage element.
 14. The system of claim 9, wherein the suction provided by the suction source is configured to draw blood through the formed at least one hole in the seal to the sensor.
 15. The system of claim 9, further comprising a conformal layer, wherein the conformal layer is configured to conform to the skin such that the suction provided by the suction source through the formed at least one hole in the seal applies suction to the skin proximate the at least one hole in the seal.
 16. A method comprising: mounting a system to skin, wherein the system comprises: a needle, wherein the needle is configured to penetrate the skin, an injector, wherein the injector is configured to drive the needle into the skin to form a puncture in the skin and subsequently to retract the needle from the skin; and a sensor, wherein the sensor is configured to detect a property of blood to which the sensor is exposed; operating the injector to drive the needle into the skin to form a puncture in the skin and subsequently to retract the needle from the skin; and operate the sensor to detect a property of blood received from the skin in response to the needle being driven into the skin.
 17. The method of claim 16, wherein the system further comprises a suction source configured to provide suction, wherein the suction provided by the suction source is configured to draw blood from the formed puncture in the skin to the sensor.
 18. The method of claim 16, wherein the injector comprises: (a) a chamber, wherein the needle is disposed at least partially within the chamber, (b) a piston disposed in the chamber, wherein the needle is coupled to the piston, and wherein the piston is configured to slidably move within the chamber, and (c) a propellant, wherein the propellant is configured to slidably move the piston within the chamber to drive the needle into skin, wherein operating the injector to drive the needle into the skin comprises igniting the propellant.
 19. The method of claim 16, wherein the system comprises a body-mountable device, wherein the body-mountable device is configured to be mounted to a surface of the skin, wherein the system further comprises a controller that is operably coupled to the sensor and the injector, wherein operating the injector to drive the needle into the skin to form a puncture in the skin and subsequently to retract the needle from the skin comprises the controller operating the injector to drive the needle into the skin at a specified point in time, and wherein operating the sensor to detect a property of blood comprises the controller operating the sensor to detect the property of blood subsequent to the specified point in time.
 20. The method of claim 19, wherein the needle, injector, and sensor are disposed in a first sampling section of the body-mountable device, and wherein the body-mountable device further comprises an additional sampling section comprising an additional needle, an additional injector, and an additional sensor, and wherein the controller is configured to: operate the additional injector, at an additional specified point in time, to drive the additional needle into the skin to form an additional puncture in the skin and subsequently to retract the additional needle from the skin; and operate the additional sensor to detect a property of blood received from the skin in response to the additional needle being driven into the skin. 